SULPHURIC ACID AND WATER. 289 
vitriol with 1 water; and the two intermediate 
mixtures will each have a bulk greater than the 
first-formed compound proportionate to the quan- 
tity of water which one contains more than the 
other,—the compound formed from 1 atom oil of 
vitriol and 2 water, will have the bulk of 824.3 
grains of water, and that of 1 atom oil of vitriol 
and 3 water, will have the bulk of 994.6 grains 
of water. Though the heat given out by making 
the mixtures must, in every instance, be the same, 
when the same relative proportions of acid and 
water are used ; yet, the indications of the ther- 
mometer immersed in the mixture must, I appre- 
hend, be liable to some modification as the bulk 
of the mixture happens to be greater or less; 
the high temperature excited being more per- 
manent as the bulk is greater, owing to the then 
less influence of the cooling agency of the sur- 
rounding atmosphere, &c. 
In all my experiments on the subject, I have 
used such proportions of acid and water as that 
the resulting compounds would, at the tempera- 
ture of 60°, be each of the same bulk, viz., equal 
to 500 grains of water. 
20 
